Air conditioning apparatus for high-speed aircraft



April 1l, 1.950 E. R. G. ECKERT 2,503,250

AIR CONDITIONING APPARATUS RoR HIGH-SPEED AIRCRAFT Filed June 2, 1948 I 3 Sheets-Sheet 2 DIE- APlil 1l, 1950 E. R. G. l-:cKl-:R-r 2,503,250

AIR CONDITIONING APPARATUS FOR HIGH-SPEED AIRCRAFT Filed June 2, 1948 3 Sheets-Sheet 3 /5 gauw l Patented Apr. 1l, 1950 AIR CONDITIONING APPARATUS FOR HIGH-SPEED AIRCRAFT ErnstR. G. Eckert, Patterson Field, Ohio Application June 2, 1948, Serial No. 30,712

5 Claims. (Cl. 62-136) (Granted under the act of- March 3, 1883, as amended April 30, 1928; 370 0. G. 757)` The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

The present invention relates to the cooling of cabins or other compartments in high velocity aircraft. I

'Ihe primary object of the invention is to provide apparatus for cooling and conditioning air for use in the cabins of high velocity aircraft and to provide simple and reliable control means for association with the conditioning apparatus.

A further object of the invention is to provide air conditioning apparatus for use with high velocity aircraft, wherein the conditioning apparatus may function entirely independently of the aircraft power plant or propulsion system` A further object of the invention is to provide air conditioning apparatus for use with high velocity aircraft, wherein the forward velocity is used to build up a pressure head for obtaining power to operate the air conditioning apparatus and also to obtain a source of air having a pressure greater than atmospheric for pressurizing the aircraft cabin.

Another object of the invention is to provide improved air conditioning apparatus for use on high velocity aircraft and thus extend the versatility and field of usefulness of aircraft carried air conditioning apparatus. K n

Another object of the invention is to provide air conditioning apparatus for high velocity aircraft including simple control means to vary the manner of operation in order to adapt the apparatus for maintaining comfort conditions in the aircraft at all altitudes normally encountered. The above and other objects of the.` invention will become apparent upon reading the following degtailed description in conjunction with the drawings, in which;

, 4 Fig. 1 is a diagrammatic cross sectionalview of a simple form of the present cabin air condi-l' tioning apparatus and including a portion of the cabin itself.

Fig. 2 is a diagrammatic cross sectional view of a second form of the present cabin air conditioning apparatus and including a portion of the, cabin having a thermostatic control means therein.

compressor of a turbojet engine for use in pressurizing as well as conditioning the air for the cabin. It is of course desirable to pressurize the cabin at high altitudes in order to supply suilicient oxygen for the aircraft pilot. It is Well recognized that altitudes of more than two miles above sea level do not represent suicient oxygen concentration for the human body to function properly, and above three miles the supply of oxygen must be augmented if the body isv to function at all. Cabin pressurizing accomplishes more than merely increasing the weight of available oxygen, since the increased pressure over that in the outside atmosphere has a beneficial eifect in maintaining pressure equilibrium in the human body. In other words pressurizing attempts to maintain or duplicate air conditions prevailing near sea level. Furthermore cooling of the air in the cabin may be required, since the cabin tends to heat up due to air friction, radiation from the sun and heat load of various electrical and mechanical equipment. Even a radio as found on board most aircraft will impose an appreciable heat load. The present air conditioning systems for aircraft do not require a turbojet engine having an air compressor, since they will function-independently of the aircraft propulsion equipment. One advantage is that the air conditioning system may be controlled.

more easily because it is not directly dependent on the output of the engine or turbo-compressor. However the principal advantage is that the air conditioning systems may be used on any high speed aircraft, regardless of the type of propul- 0 sion system present on the aircraft.v It should be emphasized also that the cooling apparatus and .pressurizing means may even nd use on board pilotless aircraft, especially whereequipment and fuels carried in the aircraft must be protected against adverse temperature and pressure` conditions. Each of the four different embodiments Fig. 3 is a diagrammatic cross sectional view 5 0 of a third form of the present cabin air conditioning apparatus.

Fig. 4 is a diagrammatic cross sectional view of a fourth form of the present cabin air conditioning apparatus.

Fig. 5 is a cross sectional view of an air valve used in the apparatus of Fig. 3.

of the invention have similarities and differences,v and each have 'particular advantages or refinements which will be noted in the 'detailed descriptions to follow.

Considering the system or apparatus of Fig. 1 it will be seen that a portion of an aircraft cabin or fuselage I carries an elongated cylindrical housing or casing 2 open at both ends for the passage of air. The housing is supported by the Ahollow struts 3 and 4 through which air may :,soaaso pass under the control of throttle valves 3' and 4'. As the aircraft moves in the direction of the arrow A the air outside the cabin enters the housing 2 at the inlet or intake 5. Rearwardly thereof the housing contains an expansion turbine 6, a cooling coil 1 receiving air from an air scoop 3, a damper valve 9, an air compressor I and an exhaust nozzle or tail cone II. Mounted on the wall of the housing is a servomotor I2 for actuating the valves 3', 4', 1' and 9 in unison, with the valves positioned as shown for one extreme of their coordinated movement. The valve 1' is adapted to control the flow of high pressure air from the coil 1 into the cabin. Mounted on the wall of the cabin is a safety valve or pressure relief valve I3, shown in detail in Fig. 6.

It will be noted that the turbine 6, which is built on the expansion principle to utilize a maximum of the energy available in the air entering the inlet 5, is provided with air guide vanes I4 fixed to the housing 2 and to a central filler and bearing member I5. The member I5 provides a forward thrust bearing for shaft I6 having turbine wheel I1 fixed thereon. The wheel I1 carries turbine blades I1' arranged on its periphery to receive air from the stationary vanes I4 and thus drive the wheel l1 and shaft I6. The extraction of energy from the air compressed ahead of the open housing 2 by the ram effect, results in a marked pressure drop through the turbine and the resulting expansion of the compressed air produces a sudden cooling action because of the loss of kinetic energy in the air. The cooled air passes over the coil 1 after also passing around the central filler and bearing member I8, thus keeping the coil much cooler than the outside atmosphere. With the various air valves in the relative positions shown, the air passes through the damper valve 9 and is then compressed by the air compressor I0. As the air leaves the compressor it passes out through exhaust nozzle II as it expands in the tail cone rearwardly of the compressor. This expansion and free discharge rearwardly of the apparatus produces a propulsive effect helping to drive the aircraft through space. Thus it may be seen that part of the kinetic energy given up by the air in passing through the expansion turbine 6 is recovered as useful work in driving the compressor I0 through the main shaft I6.

The compressor I0 is shown by way of example as including two rotor sections I9 having blades I3' on the periphery thereof. The air is guided into the rotor sections by way of blades carried on a central filler and bearing member 20. A row of stationary guide vanes 2I' on the central ller and bearing member 2| serves to take out any whirling action of the compressed air leaving the rotating blades I9', since a maximum of thrust effort can only be obtained by direct axial flow of the air through and out of the tail cone. Between the separate rows of moving blades I9' there is a row of stationary guide vanes I3" to give the air the proper direction of flow as it meets the second row of moving blades or vanes.

As the aircraft is moving forward at a rapid rate, say 600 M. P. H. or more, air is compressed within the air scoop 8 resulting in air flow through the cooling coil 1 into the. aircraft cabin I. Since the coil is cooled below the outside air temperature by air flow inside the casing 2, the air reaching the cabin by way of the cooling coil 1 will also be cooler than the ambient air and the cabin atmosphere will be cooled accordingly. At the same time the cabin air pressure is increased by the inward flow of air from the air scoop or diiusor 8. Thus the apparatus would be operating for maximum altitude conditions where deflnite cabin pressurizing is required and where the cabin cooling need only be moderate, it being well recognized that high altitude temperatures are much lower than those encountered below levels of 4000 to 6000 feet above sea level. As air pressure builds up within the cabin it is necessary to provide some avenue of escape, otherwise unnecessary stress would be put on the aircraft walls tending to burst the cabin at the weakest point. This air escape may take the form of a manually regulated valve, which may be set to allow escape of air at such a rate as to keep the inside air pressure at safe levels. However it is preferred to use an automatic air escape valve responsive to the pressure differential between the inside air and the outside air, since it is this differential which determines the stress on the aircraft wail structure. Such an automatic valve I3, which may be termed a safety valve, is shown in detail in Fig. 6 and will be described below.

As shown in Fig. 1 the shutter valves 1 and 3 are open and the shutter valves 3' and 4' are closed. The valves are arranged to be rotated to any desired setting by means of a series of cables or chains 22 forming continuous loops around pulleys or sprockets 23 fixed on the central shafts of the valve shutter elements. One of the cable loops extends over a pulley on the electrical servomotor I2, The motor is of a reversing type which may be controlled by a single-pole double-throw reversing switch 24 to operate the shutter valves 3', 4 and 3 to any desired setting. For example consider the valves in the opposite position relative to that shown in Fig. 1. With the valve 3 closed and valves 3' and 4' open, air can no longer pass through the casing 2 and over the cooling coil 1 but instead will pass into the cabin through the hollow strut 3 after being cooled by passage through the expansion turbine 5. Since the valve 4' is also open the air flowing into the cabin may displace other air which will flow out of the cabin by way of the hollow strut 4. Thence the air flows through the compressor ivto provide the same propulsive thrust as described above. With air valve 4' in open position the air flow in coil 1 is blocked by means of the coupled valve 1 in the pipe leading from the coil to the cabin I. 'I'hus no air will be brought in from the air scoop 3 and since both valves 3' and 4 are open at the same time the cabin pressure will not increase greatly over the outside air pressure. Thus with valves 3' and 4' open and valves 1 and 9 closed there will be a minimum of cabin pressurization Y and a maximum of cooling effect, a condition generally desired at lower altitudes. The valves may also be set in intermediate positions to obtain conditions between the two extremes discussed above. Using cabin temperature as the governing factor the valves may be regulated automatically by a thermostatic switch in the cabin connected in the servomotor circuit in place of the switch 24. Such a thermostatic control means will be described in connection with the other three forms of the invention, since automatic control is desirable and in practice would generally be required.

For a description of one possible form of safety valve reference is now made to Fig. 6. The valve I3 comprises a cylindrical housing 30 having a securing flange 30' for use in bolting the housing to the aircraft wall W which is cut out to receive ating diaphragm 39.

connection with Fig. 1.

the outer end portion ofthe homing.A The outer end wall of the housing is apertured to'receive `a poppet type of valve 3l having a pair of actuating rods 32 rigidly attached thereto and adapted for actuation outwardly from the position shown by a pair of levers 33. The levers 33 which are plvoted to the housing walls by means of brackets I4, are connected by links to the actuating levers It carried on xed pivots Il. The adjacent ends of levers 38 extend on opposite sidesof a stem I8 andare connected thereto by means of pin and slot connections as shown. The stem Il is attached directly to a diaphragm 39 which is clamped over the open inner end of the housing 30 by means of a recessed head plate 4l attached at its periphery to the housing by boltsl 4I. Communicating between the outside atmosphere and the space between the diaphragm and head plate is a small caliber tube 42. The housing is also provided with air holes 43 so4 that cabin air can pass into the housing freely and can also maintain cabin pressure on the outer side of the actu- Since the diaphragm is made somewhat flexible, it is obvious that when the air pressure inside the cabin rises substantially over that outside the cabin, the diaphragm 39 will bulge inwardly and actuate the various levers to open the poppet valve 3|. With valve 3i open the higher pressure air in the cabin may pass through apertures 43 into housing 30 and thence to the outer atmosphere through valve 3l. The response of the actuating diaphragm may be adjusted by properly choosing the material and dimensions of the element, and if desired its action may be stiiened by the use of springs. In any case the safety valve I3 will act to relieve excessive pressure in the cabin and prevent mechanical failure of portions of the cabin wall. Other types of safety valves may be substituted for the specific valve shown but the purpose and the response to differential pressures will still be the same.

The second form of air conditioning apparatus is illustrated in Fig. 2. While not shown as mounted on the cabin i, it is understood that the apparatus would either be enclosed in a unitary casing secured outside the cabin or built into the cabin near the forward portion thereof andy provided with the proper air inlets and outlets as required by the units comprising the air conditioning apparatus. The apparatus or system includes an air inlet and turbine housing 50 having an expansion turbine i carried centrally thereof.

lThe turbine includes a wheel 5|' mounted on a central shaft 52 having the bearing supports arranged in )a manner similar to that described in An expansion chamber rearwardly of the turbine 5I opens into a large conduit 53 ending in an exhaust nozzle 54. In order to regulate the turbine back pressure for reasons to be explained, there is a controllable l The main shaft l2 extends rearwardly from the turbine Il to drive/an-air compressor Il. 'The lcompressor, which is of the radial-flow type.

includes an impelleril rigid with shaft i2. The rear end of shaft l2 is Journaled ina central bearing Il supported by thin struts in the compressor inlet pipe 6I. The pipe Il receives ramcompressed air from the intake I2 facing directly into the alrstream. The circular or toroidal compressor manifold BI opens into a high pressure line 64 connecting with a cooling coil 65 mounted in the conduit 53. Since the expansion turbine Bi provides rapid expansion of the high pressure air entering the housing 50, thevair is cooled by passing through the turbine. The cooling coil 65 is accordingly cooled also by the passage of the expanded air thereover. The high pressure air flowing in coil 65 is cooled by transfer of heat to the coil. The coil 65 connects to the air duct B8 leading to the aircraft cabin i. Connected between the line or pipe 64 and the duct 66 there is a bypass line 61 having a throttle valve 61' mounted therein. Also a throttle valve 64 is similarly mounted in the high pressure line 64. By means of pulleys and cables the relative 'setting of valves 64' and 61' may be adjusted through the medium of a reversible servomotor 68. y Three leads 69 extend from the servomotor to a control thermostat 'l0 mounted in the aircraft cabin. Extending from the thermostat 1B are two power lines 'H connecting with a source of electric power carried on the aircraft. The heat sensitive element 'l0' of the thermostat is adapted to bend in opposite directions in response to increase or decrease of temperature and thus eil'ect control of the servomotor 68, which in turn is adapted to control the temperature of air reaching the cabin l through the high pressure duct B6.

With the temperature control valves 64' and 6l' in the positions shown, the air from compressor 58 is all routed through bypass line 6l directly into the duct 66. This air will be heated above atmospheric temperature because of the work done in compressing it in the compressor 58, not to mention the effect of ram compression ahead of the air intake 62. Therefore the apparatus will now furnish warm air to the cabin i bullet or regulator 55 mounted to 'move axially in the exhaust nozzle. A central stem 55 on the bullet is provided with rack teeth engaged by a pinion 56 carried on the shaft of a reversible servomotor 51. By proper'positioning of thebul` let 55 the cross sectional area of the exhaust nozzle may be adjusted to give the desired changes in turbine back pressure. The air expanded in the turbine 5i ilows freely from the conduit 53 at the exhaust nozzle 54, thus augmenting the propulsion system of the aircraft and making good use of some of the kinetic energy remaining in the air compressed ahead of the housingl 50 by forward motion in the direction of arrow A.

under pressure. As the cabin pressure builds up,

cessive pressure in the cabin as explained in the description of the valve itself (Fig. 6). The condition of warm air at pressures above atmospheric will be ideal for flight at high altitudes where outside temperatures may `be below zero and barometric pressure is also quite low. The. cabin will now be supercharged with ywarm air, making air conditions in the cabin comparable to those found at say 4000 feet above sea level. Now assuming that the aircraft seeks a lower altitude where the outside airis warmer. the cabin air will I soon be warm enough to actuate the thermostat 10 and motor 68 to change the relative positions of valves 64' and 6l'. With the valve 64 open partly and valve G1' closed partly, the compressed air in line 64 will ilow both through the cooling coil 65 and bypass line $1 in a definite quantity relation. The resulting fiow of cabin air in duct 66 will be at a lower temperature than in the example first given, thus lowering the temperature in the cabin and actuating thermostat 'lil to the Oil` position shown. It may be seen that the two control valves 64' and 6l' are capable of proportioning the iiow of warm and cold air to match any desired temperature condition in the cabin within reasonable limits.

, Since the flow proportioning valves 84 and 01' influence only the air temperature, it is desirable to provide other means to regulate the pressure of the air flowing in duct 55 so that the pressure may be reduced at low altitudes where atmospheric pressure is more nearly normal. For this purpose there is provided the flow regulating bullet 55 which may be set to restrict the flow oi air from the exhaust'nozzle 54. Any restriction increases the back pressure on the expansion turbine 5| to cause it to slow down, thus reducing the rotative speed of impeller 58 of compressor 58. The output pressure of the compressor 50 can thus be reduced and the air pressure in air duct E6 is reduced accordingly. If desired the servomotor 51 for actuating the bullet 55 may be automatically controlled by a barometric switch, responsive to the pressure of the atmosphere outside the aircraft. In practice such automatic control is usually required, since the aircraft personnel must be relieved of attention to details as far as possible.

The third form of air conditioning apparatus is illustrated in Fig. 3, and in general is similar to the form just described except that it provides more latitude in control of the air output and other characteristics. The apparatus comprises an air inlet and turbine housing 80 having an axial-flow expansion turbine 8| mounted therein. which is operated by air compressed ahead of the housing 80 as it moves through the atmosphere in the direction of the arrow A. V'Ihe turbine includes a turbine wheel 8|' fixed on the main shaft 82. The expanded and cooled air leaving the turbine flows into an expansion chamber and conduit 83 which terminates in an exhaust nozzle 84. The discharge area of the nozzle 84 may be adjusted by a means actuated by the servomotor 51, this portion of the apparatus being similar to the corresponding portion of the apparatus shown in Fig. 2.

The shaft 82 extends rearwardly into a radialflow air compressor 88 having an impeller 88 carried rigidly on the shaft 82 and driven by the turbine 8|. The rear end of the drive shaft 82 is supported in a central bearing 90 mounted centrally of the compressor inlet pipe 9|, the latter extending forwardly to a ram air inlet 82. The manifold 93 of the compressor is connected by a high pressure air line 94, receiving the compressor output and carrying this high pressure air to a selector valve S5 (see Fig. 5). The valve 85 may take various physical forms but for illustration the structure indicated in Fig. 5 is satisfactory. The valve body 96 has a central bore 91 having a rotatable plug 98 therein which is adapted for operation by a handle or other actuator 58. Extending through the plug 98 are a pair of curved passages and |0| adapted to connect adjacent pairs of valve ports |02, |03, |04 and |05. The rotatable valve plug is adapted to be set in two positions in a 90 relation, as shown, so as to connect ports |02 and |03, |04 and |05 in one position (solid lines) or to connect ports |02and |05, |03 and |04 in the other position (broken lines). As noted in Fig. the valve ports |02, |08, |04 and |05 connect with air conduits 84, ||0, and ||2 respectively. Thus in the position of the valve as illustrated. the compressed air from compressor 88 flows from line 54 through passage |00 and into line ||0 and thence out of the rearwardly extending discharge noazlerlll'. This free discharge of the compressed air will 8 accordingly augment the thrust of the aircraft,

' and assist the propulsion system thereof. 'Ihe conduit extends forwardly to an air scoop or air inlet and the air entering the conduit flows through the valve |0| and thence into the conduit ||2 which connects with the cooling coil ||4. The flow in conduit ||2 is controlled by means of a valve H3. The coil ||4 opens into the cabin air duct ||5, provided with a control throttle valve III'. The air conduit ||2 leading to the cooling coil is connected to the cabin air duct by a bypass duct ||0 having a control valve ||1 therein. Thus as shown in Fig. 3 all the air entering the air inlet Ill' is bypassed through conduit ||8 into the cabin duct ||5, this corresponding to a condition of the atmosphere where no cooling of the cabin is desired and only limited pressurization is needed. The air being compressed to some extent by the ram action of inlet III', the air reaching the cabin will be slightly warmer than the outside air. The valve setting of Figs. 3 and 5 might correspond to desired cabin conditioning at a moderate elevation, 'say for example '1000 to 8000 feet above sea level on a cool day, or at night.

The control valves ||3 and ||1 are controlled jointly by means of pulleys and cable loops driven by an electric servomotor 58, which is thermostatically controlled by a cabin thermostat 10 as described in connection with Fig. 2. Thus the thermostat may act to proportion warm and cold air reaching the cabin air duct I5 by way of the bypass duct ||6 and cooling coil ||4 respectively.

Now considering the apparatus of Fig. 3 with the valve 85 set in the other position, that is the broken line position of Fig. 5, it will be seen that the compressed air flowing in line 84 will pass through valve 85 to the line ||2 to form the cabin air supply while the air entering the ram inlet will flow through line valve 85 and exhaust line ||0. This valve setting will result in a maximum of cabin pressurization and with valves ||3 and ||1 in the positions shown will also result in a maximum of heating effect. Thus without changing anything except the position of valve 85, the apparatus as shown in Fig. 3 will function to overcome atmospheric conditions at high altitudes, say for example at 10,000 feet above sea level or higher. However. if the sun were shining on a summer day it would probably be necessary to open the valve ||3 partly and close valve ||1 partly to obtain cooler air. This would occur automatically by action of the thermostat 10. Excessive pressurization may be prevented by use of the adjustable exhaust nozzle 84, since raising the turbine back pressure will slow down the turbine and connected compressor 88. It is also possible to throttle the air flow for reducing cabin pressure by the proper setting of the throttle valve ||5 in the cabin air duct |'|5. If the cabin pressure should reach a level which would place too great a strain on the cabin walls, then the safety valve |3 would automatically operate to relieve the pressure by valving high pressure air in the cabin to the atmosphere. The exhaust nozzle 84 is made to have an adjustable cross section in the same manner as described in connection with Fig. 2, and as A before the servomotor 51 may be made responsive tending into another manifold |4|.

aanslaat 9 before the apparatus includes an air inlet and turbine housing which encloses an expansion turbine |2| having a single turbine wheelv |2|' mounted on the' main shaft |22. Rearwardly of the turbine there is an expansion chamber and air conduit |23 leading directly 'into a heat exchanger |24. The air forced into the air inlet by forward motion of the housing |20 at high velocity in the direction of the arrow A drives the expansion turbine at high speed, and in so doing loses its kinetic energy to such an extent as to cause substantial cooling of the air rearwardly of the turbine. The cool air passes around the tubes |25 of the heat exchanger |24 in a circuitous path and then passes out of the heat exchanger through the conduit |26. 'I'he latter conduit extends to a two-position selector valve |21, comprising a circular casing |23 having a rotatable valve body |29 mounted therein on a central shaft or pivot |30. With the valve body in the position shown, the air entering the valve from the conduit |26 is free to ow into the conduit |3| extending to the inlet side of air compressor |32. The compressor includes an impeller |33 secured on shaft |22 and driven thereby. The rearward end of shaft |22 is journaled in a central support |34 mounted in the compressor inlet. The impeller discharges air into the manifold |35 from which it is free to flow tangentially into a conduit |36 which returns the compressed air to the valve |21, and thence to the discharge conduit |31 having a discharge nozzle |31' at the rearward end thereof. As in the apparatus of Fig. 2 or Fig. 3 the cross sectional area of the discharge nozzle may be varied by means of a centrally located adjustable bullet member, the position of which may be changed by means of a servomotor 51. By regulating the discharge nozzle the back pressure on the expansion turbine |2| may be regulated, and the rotative speed thereof may be governed accordingly to govern the speed of the air compressor |32 and the pressure developed thereby.

l0 cabin Ibecomes too warm, the thermostat will act to open valve |46 partly and close valve |42' through the cable and pulley control means illus- Vtrated. Now air from the conduit |33 will iiow through the heat exchanger tubes |25 and give up v heat to the cold tubes, so that upon reaching the manifold |4| and cabin duct |43 the air will be cooler than before entering the heat exchanger.

Neglecting the heater |44, any heat in the cabin conditioning air will come as a result of compression of the air ahead of the ram inlet |36'. and while this will not be very important the heat so produced may be appreciable at high forward speeds. However the heat of compression in the air leaving the compressor |32 will be more important for cabinet heating when the selector valve |21 is turned to its other position, shown in dotted lines. In the position of the valve |21 as shown in solid lines, this heatl of compression is important in increasing the expansion of air leaving the compressor |32 and causes increased reaction effect in driving the aircraft by the free flow of expanded air from the exhaust nozzle |31. It should be noted that the solid line setting of valve |21 results in very moderate cabin pressurizing, because only the compressive effect of ram inlet |38 is available for compressing the cabin air supply. However if the cabin pressure should rise above the allowable limit, the relief valve |3 is always ready to open' and release the excessive pressure to the outside atmosphere.

Considering now the plan of operation with the valve |21 set in the second or dotted line position, it will be seen that theair leaving the heat exchanger by way of conduit |26 is directed through valve |21 to the discharge conduit |31 and thence flows from the discharge nozzle |31' to augment the thrust on the aircraft and assist the propulsion apparatus thereof in driving the aircraft through the surrounding atmosphere.

- The cabin conditioning air still originates at the Positioned to receive air by the ram effect of an inlet portion |33', is a low pressure air line |38 extending to the valve |21 and communicating with theconduit |33. 'Ihe latter conduit opens into the manifold |40 of heat exchanger |24, by which the air reaches the tubes 25 .ex-

The two manifolds |40 and |4| are connected by a bypass conduit |42, having a flow control valve M2' mounted therein. With the latter valve open as shown, the ram compressed air from conduit |39A is all bypassed from the manifold |40 to the manifold |4| and thence by conduit |43 to the aircraft cabin It may be desirable in some installations to mount an air heater |44 in the cabin duct |43 to provide for very substantial heating of the air at high laltitudes or in cold climates. The heater 44 may take any desired form, such as electrically heated grids mounted in the air stream or surface combustion units mounted in the air stream as found on some types of automobile heaters. Regulation of the cabin air pressure and volume may also be regulated by means of a throttle valve |43 mounted in the cabin air duct |43. The proportioning of cold and warm air to the cabin duct is accomplished by the relative setting of the throttle valves |40' and |42', and the setting is automatically governed by` the reversible servomotor |58k connected by leads 69 to the cabin thermostat 10 exactly like the thermostat 10 described in connection with Fig. 2, Thus if the ram inlet |33 but now passes first to the air compressor inlet by way of the conduit |33, valve |21 and conduit |3|. After being compressed in the compressor |32 the cabin air passes through conduit |36, valve |21 and conduit |33 to the`heat exchanger |24. From the manifold. |40 the compressed air is passed'through the tubes |25 or conduit |42 to the manifold |4I, conduit |43, heater |44, valve |43' and thus to the cabin or other compartment to be air conditioned. In the dotted line setting of valve member |23 there is a minimum of thrust augmentation but a maximum of cabin pressurizing. In other words this second position of the selector valve is especially suited for high altitude cabin conditioning. At high altitudes the additional pressure produced by the compressor |32 is adapted to maintain normal cabin pressure and also the heat of compression is available to warm the cabin. If this compressor-induced heat is not sufficient, then the heater |44 may also be turned on either by manual means or byvan automatic thermostatic control tied in with the main thermostat 10. Of course the proportioning valves |40 and |42' operate as explained before to give the desirable proportions of cold and warm air in the cabin conditioning air flow.

In the preceding description it was assumed for .purposes of explanation th'at the apparatus is to be usedto air condition an aircraft cabin. However other units or compartments in an aircraft may be cooled, heated and pressurized in exactly the same manner. The present apparatus is intended for general application insofar as feasible.

While the apparatus shown is not illustrated in the most compact forms possible, it is understood that in use the apparatus would be built into a unitary housing preferably for mounting within the aircraft fuselage or wing structures to eliminate unnecessary air drag. For purposes of illustration Figs. 1 to 4 show two possible forms of heat exchanger for cooling the cabin air supply. Other forms may be substituted according to choice or availability. Instead of using helically wound cooling coils as in Figs. l to 3 it may be preferable to employ spiral coils for better distribution of the cooling medium ilowing around the coils.

The embodiments of the invention herein shown and described are to be regarded as illustrative only and it is to be understood that the invention is susceptible to variations, modifications and changes within the scope of the a-ppended claims.

I claim:

1. In an air conditioning apparatus for use on high speed aircraft, means providing a forwardlyopening air inlet and chamber to receive atoms- -pheric air for ram compression thereof within said chamber and rearwardly of said inlet, an expansion turbine adapted to be driven by said ram-compressed air and to simultaneously extract kinetic energy from said air and thus cool said air, a heat exchanger to receive the cool air from said turbine and permit its flow around the cooling tubes of the heat exchanger, a rearwardly-opening nozzle to discharge the air passing from said heat exchanger and utilize the flow thereof for thrust effort on said aircraft, means providing another source of compressed air including an air compressor driven through a common shaft by said expansion turbine, means to conduct the airfrom said other source of compressed air to the cooling tubes of said heat exchanger and directly to the aircraft cabin or other space to be air conditioned, means to proportion the relative amounts of air conducted to said cooling tubes and directly to said cabin, and means to conduct the compressed air flowing from said cooling tubes to the aircraft cabin or other space to be air conditioned.

2. In an air conditioning apparatus for use on high speed aircraft as recited in claim 1, wherein said means to proportion the relative amounts of air from said other source of compressed air to said cooling tubes and directly to said cabin comprises a pair of valves having interconnected valve actuators, a reversible motor for operating said interconnected valve actuators, and a thermostatic switch located in said cabin for connecting a power source-to said servomotor for operation in the proper direction to control the cabin air temperature within predetermined limits.

3. In an air conditioning apparatus for use on high speed aircraft as recited in claim l, means to vary the cross sectional area of said rearwardlyopening discharge nozzle to vary the back pressure on said expansion turbine and thus regulate the rotative speed of said turbine and said air compressor.

4. In an air conditioning apparatus for use on high speed aircraft, means providing a forwardlyopening air inlet and chamber to receive atmospheric air for ram compression thereof within said chamber and rearwardly of said inlet, an expansion turbine adapted to be driven by said ramcompressed air and to simultaneously extract kinetic energy from said air and` thus cool said l2 air. a heat exchanger to receive the cool air from said turbine and permit its flow around the cooling tubes of the heat exchanger, a rearwardlyopening nozzle to discharge the air passing from said heat exchanger and utilize the flow thereof for thrust effort on said aircraft. a compressor driven by said expansion turbine for providing a high-pressure air source. a second forwardlyopening air inlet and chamber to receive atmospheric air for ram compression thereof within said chamber and rearwardly of said inlet for providing a low-pressure air source, a second rearwardly-opening nozzle to discharge the air from said high-pressure air source or from said low-pressure air source, a selector valve capable of being set in one position to connect said highpressure air source to said second rearwardlyopening nozzle and simultaneously connect said low-pressure air source to the cooling tubes of said heat exchanger and capable of being set in another position to connect said high-pressure air source to the cooling tubes of said heat exchanger and simultaneously connect said lowpressure air source to said second rearwardlyopening nozzle, and means to conduct the compressed air flowing from said cooling tubes to the aircraft cabin or other space to be air conditioned.

5. In an air conditioning apparatus for use on high speed aircraft, means providing a forwardlyopening air inlet and chamber to receive atmospheric air for ram compression thereof within said chamber and rearwardly of said inlet, an expansion turbine adapted to be driven by said ram-compressed air and to simultaneously extract kinetic energy from said air and thus cool saidv air, a heat exchanger to receive the cool air from said turbine and permit its flow around the cooling tubes of the'heat exchanger, a compressor driven by said expansion turbine for providing a high-pressure air sourcel a second forwardly-opening air inlet and chamber to receive atmospheric air for ram compression thereof within said chamber and rearwardly of said inlet for providing a low-pressure air source, a rearwardly-opening nomle to discharge the air leaving said heat exchanger after passing around the cooling tubes thereof or to discharge the air from said high-pressure air source,a selector valve capable of being set in one position to connect said high-pressure air source to said rearwardlyopening nozzle, to connect the air leaving said heat exchanger after passing around the cooling tubes thereof to the inlet of said compressor and to connect said low-pressure air source to the l cooling tubes of said heat exchanger and capable of being set in another position to connect said high-.pressure air source to the cooling tubes of said heat exchanger. to connect the air leaving said heat exchanger after passing around the cooling tubes thereof to said rearwardly-opening nozzle and to connect said low-pressure air source to the inlet of said compressor, and means to conduct the compressed air flowing from said cooling tubes to the aircraft cabin or other space to be air conditioned.

ERNST R.. G. ECKERT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,391,833 Kleinhans Dec. 25, 1945 2,453,923 Mayo Nov. 16, 1948 

